Long Island Sound touches two states. So it's fitting that an organization focused on protecting and restoring it now has a fixed presence in each.

Based in New Haven, Conn., Save the Sound last month opened an office in Mamaroneck and hired Tracy Brown as its western Long Island Sound director. Brown, who lives in Sleepy Hollow, hopes to champion a water quality program to improve the Sound's waters off Westchester in much the same way she did for another estuary — the Hudson River, when she was with the environmental group Riverkeeper.

It's all connected

The western section of the Sound is more likely to trap pollutants and other materials because of its narrowness and weaker currents. It can also be a dead zone with very low levels of oxygen in the summer, leading to fish kills and other ecological imbalances.

"There's not enough flushing, there's not enough movement at this end of the Sound," said Brown, whose office is a short walk from Harbor Island Park.

The Sound's western basin stretches from the Bronx to just north of Bridgeport on this side and as far east as Stony Brook on Long Island.

"If we don't triage the western basin, we won't save the central basin, the eastern basin. If it doesn't get addressed pretty quickly, it's going to bring the whole Sound down," she said.

Lots of neighbors

More than 23 million people live within 50 miles of the water, according to the Environmental Protection Agency's Long Island Sound office. Most of those live around the western section, said Curt Johnson, Save the Sound's executive director. Lots of people means lots of pollution problems, he said.

"The western basin of Long Island Sound is by far the basin that's under the greatest stress," Johnson said.

Brown's appointment — the first time in the group's 30-year history it has someone dedicated to water quality issues off Westchester and the Bronx — is a "real game-changer for the health of the western Sound," he said.

What's her plan?

High on her list is a website showing bacteria levels at local beaches during the summer. She also plans to expand a citizens' monitoring program that will search for and try to identify sources of pollution. Volunteers last year tested water at 25 points and identified several sources of fecal bacteria.

Brown will also be signing up supporters to help campaign for more state and federal money for the estuary.